The purpose of valves and chokes is to reduce the pressure or flow rate or both of a liquid. One method of reducing the pressure has been to cause the liquid to be directed in a manner that it impinges on itself. This increases velocity by increasing the flow through an orifice which dissipates energy.
Other prior art methods of reducing pressure have had problems in that the pressure could be reduced only by a certain amount in a single stage. A prior attempt at solving this problem was to use several stages to reduce the pressure. A problem with reducing the pressure in several stages is that the prior art stages are often bulky and cumbersome and resulted in a large valve.